The invention relates to a cable winch.
German laid-open document DE 34 24 590 A1 already discloses a chain hoist comprising an electric drive motor. The drive motor is connected by means of a transmission to a chain wheel for driving a chain. The transmission typically has a transmission input shaft, at the end of which opposite the drive motor a disk is connected for conjoint rotation therewith. The disk is a component part of a sensor arrangement for determining the rotational speed of the transmission input shaft which includes a sensor which operates according to the Hall effect. For this purpose, magnets are embedded along the circumference of the disk at mutually spaced intervals, said magnets being detected by the Hall sensor when they move past the Hall sensor by rotation of the transmission input shaft.
Furthermore, European patent application EP 0 476 459 A2 describes a safety apparatus for cranes in which a rotational speed sensor and a rotation angle sender are allocated to an electric drive motor and additionally also to a cable drum. The rotational speed sensors are designed as incremental sensors and the rotation angle senders are designed as angle encoders. Neither rotational speed sensors nor rotation angle senders are provided in the region of a transmission between the drive motor and the cable drum.
Furthermore, German patent application DE 103 39 440 A1 discloses a method of monitoring a chain hoist which evaluates a signal of a rotational speed sensor. The rotational speed sensor is arranged at one end of an input shaft of a transmission which is opposite an electric drive motor. The rotational speed sensor is designed as a light barrier which engages in a bifurcated manner around an outer edge of a serrated lock washer. The serrated lock washer is connected to the input shaft of the transmission for conjoint rotation therewith and is provided at its outer edge region with substantially rectangular teeth which are distributed uniformly along the circumference of the serrated lock washer and alternate with substantially rectangular apertures. The interruptions in the light beam caused by the teeth of the serrated lock washer moving past are evaluated as the signal.
The arrangement of a rotary encoder between a drive motor and a transmission is known from JP 2010-200 543 A in relation to the steering drive of a vehicle, and is known from DE 197 49 009 A1 in relation to the actuating drive of electric window lifts and mirror adjusters of vehicles. A corresponding arrangement is also known from JP 2001-103 709 A.
A cable winch is already known from US 2005/0072965 A1. A further cable winch comprising a rotary encoder is known from EP 2 179 959 A1.